The present application generally relates to methods and apparatus for transfer of films from one or mare substrates to another.
In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowtedge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.
The discovery of graphene has generated widespread interest for potential use in electronic and other applications due to its electronic, optical, physical, and mechanical properties. Graphene is a single atomic layer of carbon atoms, tightly bonded in a hexagonal lattice. Despite its short history as an experimental system, graphene has already revealed exciting new physics including “relativistic” carriers with implications for quantum electronic transport and charge screening, a width-dependent energy band gap, extremely high carrier mobility, high elasticity and electromechanical modulation. The properties of graphene appeal to many industries, in particular electronics. Graphene's high carrier mobility and high thermal conductivity make it a potential alternative to silicon and diamond. Its properties may enable the creation of next generation solid-state devices (ballistic transistors, spin transistors, etc.). Graphene is also a candidate for use as a flexible, optically transparent conductor in applications such as touch displays and photovoltaics. Other potential applications include chemical sensors, nanopore filters, impermeable coatings for corrosion and/or chemical protection, ultracapacitors, TEM supports, and others.
The goal of low cost graphene sheets has driven recent research in methods of large area graphene production. Chemical vapor deposition of graphene on metal substrates is one promising method for large area, low cost, graphene production. One critical issue of graphene production is the handling of the graphene films and the transfer of those films from the deposition substrate to other substrates for many applications. Accordingly, there is a need for a large area process to transfer single layer or multi-layer graphene from one substrate to another substrate.
One current, widely used graphene transfer process includes a chemical etching step to remove the metal substrate by dissolution. Scaling this process to thousands of square meters production, leads to great expense and waste challenges. The reclamation or disposal of metal infused etchant constitutes a major cost and waste handling issue. Since the substrate is dissolved by the etchant, it cannot be reused for the growth of graphene films. In addition, the dissolution process is rather slow. For at least these reasons, this conventional technique is not well-suited for efficient, large-scale, low cost production of graphene films.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention. Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass or include one or more of the conventional technical aspects discussed herein.